Embodiments of the present invention relate to a method for starting a gas turbine. Such method is potentially applicable to every kind of gas turbine, such as the ones used for mechanical power (compressors or pumps drive) and for power generation (electrical generators).
A gas turbine is known from the state of the art, comprising a combustion chamber provided with one or more nozzles. Such nozzles are used to inject fuel, which is then burned inside the combustion chamber. The hot exhaust gases that exit the combustion chamber are then used to move an impeller attached to a shaft, thus providing mechanical work.
An apparatus for regulating the flow of fuel in such gas turbine is also known. The apparatus comprises a fuel line, which in operation is connected with a fuel inlet and with the nozzles of the gas turbine. Indeed, the fuel line has the function of transferring fuel from the inlet to the nozzles. A regulating valve is placed along the fuel line, so that the flow of fuel can be controlled. Thus, in order to start the turbine, the regulating valve is opened to a defined stroke and a small flow of fuel is allowed to enter inside the combustion chamber. A spark then ignites the fuel and, afterwards, the flow of fuel can be increased further, until a desired operating condition is achieved.
An aspect of the prior art is that, in case of a malfunction of the regulating valve, too much fuel can be allowed inside the combustion chamber before the ignition. This is potentially extremely dangerous, as it can lead to an explosion of the gas turbine or its exhaust duct with high risk of injuries or fatalities of personnel. For this reason, the known turbines are provided with a safety device designed to interrupt the flow of fuel in case of malfunction. Indeed, such safety device may comprise a flow meter placed on the fuel line downstream of the regulating valve